Sound Damping Gypsum Board and Method of Constructing a Sound Damping Gypsum Board

ABSTRACT

The present invention is directed to an improved gypsum board, such as an improved sound damping gypsum board, and a method of making such gypsum board. For instance, the method comprises: providing a first encasing layer and a first sound damping layer on the first encasing layer wherein the sound damping layer includes at least 50 wt. % of a first sound damping polymer; depositing a gypsum slurry comprising stucco and water on the sound damping layer to form a gypsum core; providing a second encasing layer on the gypsum slurry; and allowing the stucco to convert to calcium sulfate dihydrate.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims filing benefit of U.S. Provisional PatentApplication Ser. No. 63/035,203 having a filing date of Jun. 5, 2020,and which is incorporated herein by reference in its entirety.

BACKGROUND

A building is typically constructed with walls having a frame comprisingvertically oriented studs connected by horizontally oriented top andbottom plates or tracks. The walls often include one or more gypsumboards fastened to the studs and/or plates on each side of the frame or,particularly for exterior walls, one or more gypsum boards fastened tothe studs and/or plates on one side of the frame with a non-gypsum basedsheathing attached to an exterior side of the frame. A ceiling of thebuilding may also include one or more gypsum boards orientedhorizontally and fastened to joists, studs, or other structural membersextending horizontally in the building. Walls and ceilings of thisconstruction often have poor acoustical performance and a low soundtransmission class (STC) rating, which results in noise pollution, lackof privacy, and similar issues in the various spaces of the building.One of the aspects of this poor performance is the coincidence betweenthe human voice Hertz spectrum and the vibrational Hertz range ofstandard gypsum board, which creates a unique dip in the acousticalcurve of a standard frame and gypsum board wall.

While boards currently exist that provide sound damping, there is stilla need to further improve the acoustical performance of the boards andprovide improved sound damping.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a method offorming a gypsum board is disclosed. The method comprises: providing afirst encasing layer and a first sound damping layer on the firstencasing layer wherein the sound damping layer includes at least 50 wt.% of a first sound damping polymer; depositing a gypsum slurrycomprising stucco and water on the sound damping layer to form a gypsumcore; providing a second encasing layer on the gypsum slurry; andallowing the stucco to convert to calcium sulfate dihydrate.

In accordance with another embodiment of the present invention, a gypsumboard is disclosed. The gypsum board is formed by the following method:providing a first encasing layer and a first sound damping layer on thefirst encasing layer wherein the sound damping layer includes at least50 wt. % of a first sound damping polymer; depositing a gypsum slurrycomprising stucco and water on the sound damping layer to form a gypsumcore; providing a second encasing layer on the gypsum slurry; andallowing the stucco to convert to calcium sulfate dihydrate.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments, one or moreexamples of which may be illustrated in any drawings. Each example isprovided by way of explanation of the embodiments, not as a limitationof the present disclosure. In fact, it will be apparent to those skilledin the art that various modifications and variations can be made to theembodiments without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that aspects of the presentdisclosure cover such modifications and variations.

Generally speaking, the present invention is directed to a gypsum board,such as an improved sound damping gypsum board, and a method of makingsuch gypsum board. In particular, the present invention is directed tothe application of a sound damping polymer on an encasing layer prior todeposition of a gypsum slurry for producing the gypsum core. In thisregard, the sound damping polymer may be present between the encasinglayer and the gypsum core. The present inventors have discovered thatvarious benefits may also be realized. For instance, improvements in theacoustical performance of the gypsum board may be realized by theminimization of sound transmission through a wall containing such gypsumboards. In addition, such application of the sound damping polymer mayalso assist with simplifying the manufacturing process in comparison tocertain conventional techniques.

For instance, in comparison to conventional gypsum board, in particularan existing, installed gypsum board without a sound damping layer, thesound damping gypsum board as disclosed herein would exhibit a soundtransmission loss of 5% or more, such as 10% or more, such as 15% ormore, such as 20% or more, such as 25% or more, such as 30% or more,such as 35% or more, such as 40% or more, such as 45% or more, such as50% or more and less than 100%, such as less than 90%, such as less than80%, such as 70% or less, such as 60% or less in comparison to theconventional gypsum board without a sound damping layer. Such comparisonmay be at any frequency and in particular at a frequency of 100 Hz ormore, such as 125 Hz or more, such as 500 Hz or more, such as 1000 Hz ormore, such as 2000 Hz or more, such as 2500 Hz or more, such as 3150 Hzor more, such as 4000 Hz or more. In particular, such comparison may beat 100 Hz, such as 125 Hz, such as at 500 Hz, such as at 1000 Hz, suchas at 2000 Hz, such as at 2500 Hz, such as at 3150 Hz, such as at 4000Hz. In addition, such comparison may be at any 2, such as at any 3, suchas at any 4, such as at any 5 of the aforementioned frequencies.

Further, the sound transmission loss for a wall assembly including thesound damping gypsum board as disclosed herein may be 1% or more, suchas 2% or more, such as 5% or more, such as 10% or more, such as 15% ormore, such as 20% or more, such as 30% or more than the soundtransmission loss for a wall assembly not including a sound dampinglayer as disclosed herein. Such comparison may be at any frequency andin particular at a frequency of 500 Hz or more, such as 1000 Hz or more,such as 2000 Hz or more, such as 2500 Hz or more, such as 4000 Hz ormore. In particular, such comparison may be at 500 Hz, such as at 1000Hz, such as at 2000 Hz, such as at 2500 Hz, such as at 4000 Hz. Inaddition, such comparison may be at any 2, such as at any 3, such as atany 4, such as at any 5 of the aforementioned frequencies.

In addition, at a frequency of 1000 Hz, the sound transmission loss ofthe sound damping gypsum board as disclosed herein may be 40 dB or more,such as 45 dB or more, such as 50 dB or more, such as 55 dB or more,such as 56 dB or more, such as 57 dB or more, such as 58 dB or more,such as 60 dB or more. At a frequency of 2000 Hz, the sound transmissionloss of the sound damping gypsum board as disclosed herein may be morethan 40 dB, such as 45 dB or more, such as 50 dB or more, such as 51 dBor more, such as 52 dB or more, such as 53 dB or more, such as 55 dB ormore, such as 57 dB or more. At a frequency of 4000 Hz, the soundtransmission loss of the sound damping gypsum board as disclosed hereinmay be more than 40 dB, such as 45 dB or more, such as 50 dB or more,such as 52 dB or more, such as 53 dB or more, such as 55 dB or more,such as 57 dB or more, such as 59 dB or more, such as 60 dB or more.

In general, the present invention is directed to a sound damping gypsumboard and a method of making such gypsum board. For instance, in themethod of making a sound damping gypsum board, a first encasing layermay be provided wherein the first encasing layer has a first encasinglayer surface and a second encasing layer surface opposite the firstencasing layer surface. The first encasing layer may be conveyed on aconveyor system (i.e., a continuous system for continuous manufacture ofgypsum board). In addition, a sound damping polymer as disclosed hereinmay be provided on the first encasing layer surface. For instance, thesound damping polymer may be provided on the first encasing layersurface offline such that it is already provided on the first encasinglayer prior to use in the manufacture of the gypsum board.Alternatively, or in addition, the sound damping polymer may be providedinline during the manufacture of the gypsum board. In this regard, inone embodiment, the sound damping polymer may already be set on theencasing layer prior to deposition of the gypsum slurry. In anotherembodiment, the sound damping polymer may not already be set on theencasing layer prior to deposition of the gypsum slurry.

When providing the sound damping polymer, it may be applied using meansknown in the art, such as roll coating, spraying, etc. The sound dampingpolymer may be applied to form a continuous layer, to form a pattern, orin a random manner. For example, the pattern may be a grid pattern. Inaddition, it should be understood that the pattern may be a regularpattern or an irregular pattern. Furthermore, by forming a pattern orapplying the sound damping polymer in a random manner, such applicationmay result in a discontinuous sound damping layer. Also, when providingthe sound damping polymer, it may be utilized according to thedisclosure provided above or below to achieve the desired sound dampingproperties.

The sound damping polymer may be any polymer that can provide animproved acoustical performance or sound damping effect. For instance,the sound damping polymer may comprise a thermoplastic polymer or athermoset polymer. In one embodiment, the sound damping polymercomprises a thermoplastic polymer. In another embodiment, the sounddamping polymer comprises a thermoset polymer. In one particularembodiment, the sound damping polymer may be an elastomer, in particulara thermoplastic elastomer.

Suitable sound damping polymers include, as non-limiting examples,synthetic resins, polymers and copolymers, and latex polymers as areknown in the art. In a preferred embodiment, the sound damping polymeris an acrylic (or acrylate) polymer or copolymer. One such non-limitingexample is Acronal®, an acrylate copolymer commercially available fromBASF (Charlotte, N.C.). Another non-limiting example is QuietGlue™,which includes an acrylic (or acrylate) polymer and in particular two ofsuch polymers. The formulation for QuietGlue™ can be found in U.S. Pat.No. 7,921,965, which is incorporated herein by reference in itsentirety. Other examples of polymers may include, but are not limitedto, styrene acrylics, acrylic esters, vinyl acrylics, vinyl chlorideacrylics, styrene acetate acrylics, ethylene polyvinyl acetate,polyvinyl acetate, styrene butadiene, etc. When provided in aformulation, the concentration of the sound damping polymer may notnecessarily be limited. However, such formulation should have sufficientfluidity (e.g., with the presence of water) to allow for the formulationand polymer to be handled and processed for incorporation into thegypsum slurry. Alternatively, because the sound damping polymer may beapplied at an interface, it should also have sufficient fluidity forapplication at an interface of an encasing layer and the gypsum slurry.

In addition, it should be understood that the sound damping polymer mayinclude more than one different sound damping polymers. For instance, inone embodiment, at least two sound damping polymers may be provided ontothe first encasing layer.

In one or more embodiments, the sound damping material comprises apolymer having a dynamic glass transition temperature at or below theworking temperature at which the sound damping layer will be used. Forinstance, the working temperature may be the temperature at which thesound damping polymer will be utilized. In this regard, in oneembodiment, the sound damping polymer may be provided as a glue, such asa viscoelastic glue. Such glue may be provided onto the encasing layerfor forming a sound damping layer.

In addition, the sound damping polymer may have a relatively low glasstransition temperature. For instance, the polymer may have a glasstransition temperature of room temperature or less. For instance, thepolymer may have a glass transition temperature of 25° C. or less, suchas 20° C. or less, such as 10° C. or less, such as 5° C. or less, suchas 1° C. or less, such as 0° C. or less, such as −5° C. or less, such as−10° C. or less, such as −15° C. or less, such as −20° C. or less, suchas −25° C. or less, such as −30° C. or less, such as −35° C. or less,such as −40° C. or less, such as −50° C. or less. The polymer may have aglass transition temperature of −90° C. or more, such as −80° C. ormore, such as −75° C. or more, such as −70° C. or more, such as −65° C.or more, such as −60° C. or more, such as −55° C. or more, such as −50°C. or more, such as −40° C. or more, such as −30° C. or more.

The sound damping polymer may be present in an amount of 0.001 lbs/MSFor more, such as 0.01 lbs/MSF or more, such as 0.05 lbs/MSF or more,such as 0.1 lbs/MSF or more, such as 0.2 lbs/MSF or more, such as 0.25lbs/MSF or more, such as 0.5 lbs/MSF or more, such as 0.75 lbs/MSF ormore, such as 1 lb/MSF or more, such as 1.5 lbs/MSF or more, such as 2lbs/MSF or more, such as 2.5 lbs/MSF or more, such as 3 lbs/MSF or more,such as 4 lbs/MSF or more. The sound damping polymer may be present inan amount of 150 lbs/MSF or less, such as 100 lbs/MSF or less, such as50 lbs/MSF or less, such as 25 lbs/MSF or less, such as 15 lbs/MSF orless, such as 10 lbs/MSF or less, such as 5 lbs/MSF or less, such as 4lbs/MSF or less, such as 3 lbs/MSF or less, such as 2.5 lbs/MSF or less,such as 2 lbs/MSF or less, such as 1.5 lbs/MSF or less, such as 1lbs/MSF or less. Such MSF value may be the weight of the gypsum board inone embodiment. In another embodiment, such MSF value may be the weightof the gypsum within the gypsum core.

The sound damping polymer may be provided as a formulation that may alsocomprise various additives, including anti-microbial materials forfungal protection and appropriate fillers such as, in non-limitingexamples, vermiculite, expanded mica, perlite, talc, lead, andgranulated polystyrene aluminum oxide. Additional embodiments include atacky adhesive constructed of one or more polymers having fluidity at anordinary temperature and one or more emulsion type or solvent typepolymers consisting of one or more natural rubbers, synthetic rubbers,and polymers such as, in non-limiting examples, acrylic resin andsilicone resin. A tackifier, including such non-limiting examples aspetroleum resin and sap, a softener, and/or a plasticizer are includedin the sound damping layer in one or more embodiments of the presentdisclosure. Other non-limiting examples of additives used to form thesound damping material include polyester resins, resins constructed fromplasticizers or peroxide being added to polyester, multiple polyesters,polyurethane foam, polyamide resin, ethylene-vinyl acetate copolymers,ethylene acrylic acid copolymers, polyurethane copolymers, and EPDMpolymers. In addition, other additives may include one or more additivesthat are conventionally used within the gypsum core (e.g., calciumsulfate hemihydrate, calcium sulfate dihydrate, natural polymers such asstarches, phosphates, and the like). In one embodiment, such additivesmay include cellulosic materials such as cellulose fibers,microcellulose, nanocellulose, and the like. The additives may includecoated and uncoated inorganic materials (e.g., porous siliceousmaterials, minerals, and the like). The additives may include plated orhollow materials such as mica, graphite, micro-glass flakes, glassmicro- or nanobubbles, or mixtures thereof. The additives may includedensity altering materials such as barium sulfate, fly ash, calciumcarbonate, magnesium carbonate, rubber (e.g., ground or cut rubber),cork, mixtures thereof, and the like. In addition, the sound dampinglayer may include a pigment. Also, as indicated above, the sound dampinglayer may include an inorganic particle. The additives may includeporous natural materials such as wood chips, saw dust, rice husks, otherfibrous materials, etc., and mixtures thereof. The additives may includethose that alter the fluidity such as surfactants, dispersants,thickening agents, and/or fluidizing agents (e.g., glycerin, ethoxylatedglycerin, etc.). The additives may include those that alter the rate anddegree of curing and adhesion such as tackifiers.

The formulation including the sound damping polymer may also have acertain viscosity. For instance, the viscosity may be 500 cps orgreater, such as 1000 cps or greater, such as 2000 cps or greater, suchas 3000 cps or greater, such as 4000 cps or greater, such as 5000 cps orgreater, such as 6000 cps or greater, such as 7000 cps or greater. Theviscosity may be 15000 cps or less, such as 13000 cps or less, such as11000 cps or less, such as 10000 cps or less, such as 9000 cps or less,such as 8000 cps or less, such as 7000 cps or less, such as 6000 cps orless, such as 5000 cps or less, such as 4000 cps or less, such as 3000cps or less, such as 2000 cps or less, such as 1500 cps or less, such as1000 cps or less. The viscosity may be determined using a Brookfieldviscometer with a #4 spindle, a speed of 30 rpm, and 500 mL offormulation.

In one embodiment, the sound damping layer may include at least one ofgypsum, calcium carbonate, magnesium carbonate, pigment, polyurea, or aninorganic particle. For instance, the sound damping layer may include atleast gypsum. In another embodiment, the sound damping layer may includeat least calcium carbonate. In a further embodiment, the sound dampinglayer may include at least magnesium carbonate. In another furtherembodiment, the sound damping layer may include at least one pigment. Inan even further embodiment, the sound damping layer may includepolyurea. In another embodiment, the sound damping layer may include aninorganic particle. In addition, it should be understood that the sounddamping layer may include any two of the aforementioned in combination.Further, the sound damping layer may include any three of theaforementioned in combination.

The sound damping polymer may also be provided with or used inconjunction with materials or additives that may provide different sounddamping effects and performance. For instance, with respect to suchadditives, one may have a higher density than the other additive. Theseadditives may include, but are not limited to, microspheres (e.g.,hollow microspheres, filled microspheres), glass spheres, cenospheres,waste materials, minerals (e.g., high density, low density), metals,etc.

Regardless of the above, these additives may be utilized in amounts toobtain the desired properties. For instance, these additives, alone orin combination, may be present in an amount of 0.001 lbs/MSF or more,such as 0.01 lbs/MSF or more, such as 0.05 lbs/MSF or more, such as 0.1lbs/MSF or more, such as 0.2 lbs/MSF or more, such as 0.25 lbs/MSF ormore, such as 0.5 lbs/MSF or more, such as 0.75 lbs/MSF or more, such as1 lb/MSF or more, such as 1.5 lbs/MSF or more, such as 2 lbs/MSF ormore, such as 2.5 lbs/MSF or more, such as 3 lbs/MSF or more, such as 4lbs/MSF or more. These additives, alone or in combination, may bepresent in an amount of 150 lbs/MSF or less, such as 100 lbs/MSF orless, such as 50 lbs/MSF or less, such as 25 lbs/MSF or less, such as 15lbs/MSF or less, such as 10 lbs/MSF or less, such as 5 lbs/MSF or less,such as 4 lbs/MSF or less, such as 3 lbs/MSF or less, such as 2.5lbs/MSF or less, such as 2 lbs/MSF or less, such as 1.5 lbs/MSF or less,such as 1 lbs/MSF or less. Such MSF value may be the weight of thegypsum board in one embodiment. In another embodiment, such MSF valuemay be the weight of the gypsum within the gypsum core.

As indicated above, the sound damping layer includes the sound dampingpolymer and may include other additives. Regardless, the sound dampinglayer may include the sound damping polymer in an amount of 50 wt. % ormore, such as 60 wt. % or more, such as 70 wt. % or more, such as 75 wt.% or more, such as 80 wt. % or more, such as 85 wt. % or more, such as90 wt. % or more, such as 95 wt. % or more. The sound damping polymermay be present in an amount of 100 wt. % or less, such as 99.5 wt. % orless, such as 99 wt. % or less, such as 98.5 wt. % or less, such as 98wt. % or less, such as 97.5 wt. % or less, such as 95 wt. % or less,such as 93 wt. % or less, such as 90 wt. % or less. In this regard, thesound damping layer may include any of the aforementioned additives,alone or in combination, in an amount of 50 wt. % or less, such as 40wt. % or less, such as 30 wt. % or less, such as 25 wt. % or less, suchas 20 wt. % or less, such as 15 wt. % or less, such as 10 wt. % or less,such as 8 wt. % or less, such as 6 wt. % or less, such as 5 wt. % orless, such as 4 wt. % or less, such as 3 wt. % or less, such as 2 wt. %or less, such as 1 wt. % or less. When such additives are utilized, theymay be present, alone or in combination, in such layer in an amount of0.001 wt. % or more, such as 0.01 wt. % or more, such as 0.1 wt. % ormore, such as 0.2 wt. % or more, such as 0.4 wt. % or more, such as 0.5wt. % or more, such as 1 wt. % or more, such as 1.5 wt. % or more, suchas 2 wt. % or more, such as 2.5 wt. % or more, such as 3 wt. % or more,such as 5 wt. % or more, such as 8 wt. % or more, such as 10 wt. % ormore.

With the sound damping polymer on the first encasing layer, a gypsumslurry may then be provided to form a gypsum core. In this regard, themethod may comprise a step of depositing a gypsum slurry onto the firstencasing layer, in particular the sound damping layer formed from thesound damping polymer on the first encasing layer. In general, thecomposition of the gypsum core is not necessarily limited and may be anygypsum core generally known in the art. Generally, in one embodiment,the gypsum core is made from a gypsum slurry including at least stuccoand water. In this regard, the method may also include a step ofcombining stucco, water, and any other optional additives as mentionedherein.

In general, stucco may be referred to as calcined gypsum or calciumsulfate hemihydrate. The calcined gypsum may be from a natural source ora synthetic source and is thus not necessarily limited by the presentinvention. In addition to the stucco, the gypsum slurry may also containsome calcium sulfate dihydrate or calcium sulfate anhydrite. If calciumsulfate dihydrate is present, the hemihydrate is present in an amount ofat least 50 wt. %, such as at least 60 wt. %, such as at least 70 wt. %,such as at least 80 wt. %, such as at least 85 wt. %, such as at least90 wt. %, such as at least 95 wt. %, such as at least 98 wt. %, such asat least 99 wt. % based on the weight of the calcium sulfate hemihydrateand the calcium sulfate dihydrate. Furthermore, the calcined gypsum maybe α-hemihydrate, β-hemihydrate, or a mixture thereof.

In addition to the stucco, the gypsum slurry may also contain otherhydraulic materials. These hydraulic materials may include calciumsulfate anhydrite, land plaster, cement, fly ash, or any combinationsthereof. When present, they may be utilized in an amount of 30 wt. % orless, such as 25 wt. % or less, such as 20 wt. % or less, such as 15 wt.% or less, such as 10 wt. % or less, such as 8 wt. % or less, such as 5wt. % or less based on the total content of the hydraulic material.

As indicated above, the gypsum slurry may also include water. Water maybe employed for fluidity and also for rehydration of the gypsum to allowfor setting. The amount of water utilized is not necessarily limited bythe present invention.

In addition, the weight ratio of the water to the stucco may be 0.2 ormore, such as 0.2 or more, such as 0.3 or more, such as 0.4 or more,such as 0.5 or more. The water to stucco weight ratio may be 4 or less,such as 3.5 or less, such as 3 or less, such as 2.5 or less, such as 2or less, such as 1.7 or less, such as 1.5 or less, such as 1.4 or less,such as 1.3 or less, such as 1.2 or less, such as 1.1 or less, such as 1or less, such as 0.9 or less, such as 0.85 or less, such as 0.8 or less,such as 0.75 or less, such as 0.7 or less, such as 0.6 or less, such as0.5 or less, such as 0.4 or less, such as 0.35 or less, such as 0.3 orless, such as 0.25 or less, such as 0.2 or less.

In one embodiment, the gypsum core may also include a sound dampingpolymer as mentioned above. For instance, the sound damping polymer maybe provided by mixing the sound damping polymer directly with the stuccoand water to form the gypsum slurry. In addition to the sound dampingpolymer, if providing the sound damping polymer as a formulation orcomposition, other additives as mentioned above may also be utilized.

When present, the sound damping polymer may be present in the gypsumcore in an amount to provide a desired sound damping effect. When makingthe board, the sound damping polymer may be present in an amount of0.001 wt. % or more, such as 0.01 wt. % or more, such as 0.02 wt. % ormore, such as 0.05 wt. % or more, such as 0.1 wt. % or more, such as0.15 wt. % or more, such as 0.2 wt. % or more, such as 0.25 wt. % ormore, such as 0.3 wt. % or more, such as 0.5 wt. % or more based on theweight of the stucco. The sound damping polymer may be present in anamount of 10 wt. % or less, such as 7 wt. % or less, such as 5 wt. % orless, such as 4 wt. % or less, such as 3 wt. % or less, such as 2.5 wt.% or less, such as 2 wt. % or less, such as 1.8 wt. % or less, such as1.5 wt. % or less, such as 1 wt. % or less, such as 0.8 wt. % or less,such as 0.6 wt. % or less, such as 0.5 wt. % or less, such as 0.4 wt. %or less, such as 0.35 wt. % or less, such as 0.2 wt. % or less based onthe weight of the stucco. In addition, the aforementioned weightpercentages may also apply based on the weight of the gypsum in thegypsum board. In addition, the aforementioned weight percentages mayalso apply based on the weight of the gypsum board.

In addition to the stucco and the water, the gypsum slurry may alsoinclude any other conventional additives as known in the art. In thisregard, such additives are not necessarily limited by the presentinvention. For instance, the additives may include dispersants, foam orfoaming agents including aqueous foam (e.g. sulfates), set accelerators(e.g., BMA, land plaster, sulfate salts, etc.), set retarders, binders,biocides (such as bactericides and/or fungicides), adhesives, pHadjusters, thickeners (e.g., silica fume, Portland cement, fly ash,clay, celluloses, high molecular weight polymers, etc.), levelingagents, non-leveling agents, starches (such as pregelatinized starch,non-pregelatinized starch, and/or an acid modified starch), colorants,fire retardants or additives (e.g., silica, silicates, expandablematerials such as vermiculite, perlite, etc.), water repellants, fillersand fibers (e.g., glass fibers), waxes, secondary phosphates (e.g.,condensed phosphates or orthophosphates including trimetaphosphates,polyphosphates, and/or cyclophosphates, etc.), mixtures thereof, naturaland synthetic polymers, etc. In general, it should be understood thatthe types and amounts of such additives are not necessarily limited bythe present invention.

In general, each additive may be present in the gypsum slurry in anamount of 0.0001 wt. % or more, such as 0.001 wt. % or more, such as0.01 wt. % or more, such as 0.02 wt. % or more, such as 0.05 wt. % ormore, such as 0.1 wt. % or more, such as 0.15 wt. % or more, such as 0.2wt. % or more, such as 0.25 wt. % or more, such as 0.3 wt. % or more,such as 0.5 wt. % or more, such as 1 wt. % or more, such as 2 wt. % ormore based on the weight of the stucco. The additive may be present inan amount of 20 wt. % or less, such as 15 wt. % or less, 10 wt. % orless, such as 7 wt. % or less, such as 5 wt. % or less, such as 4 wt. %or less, such as 3 wt. % or less, such as 2.5 wt. % or less, such as 2wt. % or less, such as 1.8 wt. % or less, such as 1.5 wt. % or less,such as 1 wt. % or less, such as 0.8 wt. % or less, such as 0.6 wt. % orless, such as 0.5 wt. % or less, such as 0.4 wt. % or less, such as 0.35wt. % or less, such as 0.2 wt. % or less based on the weight of thestucco.

The manner in which the components for the gypsum slurry are combined isnot necessarily limited. For instance, the gypsum slurry can be madeusing any method or device generally known in the art. In particular,the components of the slurry can be mixed or combined using any methodor device generally known in the art. For instance, the components ofthe gypsum slurry may be combined in any type of device, such as a mixerand in particular a pin mixer. In this regard, the manner in which thesound damping polymer is incorporated into the gypsum slurry is notnecessarily limited by the present invention. When a sound dampingpolymer is provided in the gypsum slurry as well, it may be providedprior to a mixing device, directly into a mixing device, and/or evenafter the mixing device. For instance, the sound damping polymer may beprovided prior to a mixing device. In another embodiment, the sounddamping polymer may be provided directly into a mixing device.Alternatively, the sound damping polymer may be provided after themixing device (such as to the canister or boot, using a secondary mixer,or applied directly onto the slurry after a mixing device) and may beadded directly or as part of a mixture. Whether provided prior to, into,or after the mixing device, the sound damping polymer may be combineddirectly with another component of the gypsum slurry. In addition,whether providing the sound damping polymer prior to or after the mixingdevice or directly into the mixing device, the compound may be deliveredas a solid, as a dispersion/solution, or a combination thereof.

When provided in the gypsum core, the sound damping polymer may beprovided with a carrier material. For instance, the carrier material maybe a material to assist in the delivery of the sound damping polymer.The carrier material may be a liquid, a solid, or a mixture thereof. Inone embodiment, the carrier material comprises a solid. In anotherembodiment, the carrier material comprises at least a liquid. Inparticular, the sound damping polymer may be delivered or provided assolution, an emulsion or a dispersion.

The carrier material may include any of the additives as mentioned aboveand considered herein. For instance, the carrier material may be aplasticizer (e.g., glycerin and/or it's ethoxylated derivatives,dicarboxylic/tricarboxylic ester-based plasticizers such as phthalates,trimellitates, adipates, sebacates, maleates, azelates, benzoates,terephthalates, sulfonamides, organophosphates, glycols and polyethers,etc., and mixtures thereof), a soap or foaming agent (e.g., sulfatessuch as ammonium ether sulfates and alkyl ether sulfates includinglaureth sulfates, laureth ether sulfates, and lauryl sulfates;sulfonates; sulfosuccinates; sulfolaurates; alcohol ethoxylates; amineoxides; betaines; etc. and mixtures thereof), a dispersant, a starch, apolymer (e.g., a thermoplastic polymer such as polystyrene), fillermaterials (e.g., perlite, vermiculite, clay such as expanded clay,hollow microspheres, etc.).

As indicated above, the carrier may include a plasticizer, a foamingagent, and/or a dispersant. In this regard, the carrier may be anionic,nonionic, or amphoteric or the carrier may include mixtures thereof. Inone embodiment, the carrier may include at least an anionic. In anotherembodiment, the carrier may include at least a nonionic. In a furtherembodiment, the carrier may include at least an amphoteric.

Also, the carrier may be a starch. The starch may be a migrating starchsuch that it migrates. Because of such migration, the starch may assistwith moving the sound damping polymer within the gypsum core. Forinstance, the starch may assist with moving the sound damping polymertowards the interface between the gypsum core and the encasing material.Alternatively, the starch may be a non-migrating starch. In addition,the starch may be any as known in the art. The starch may be anunmodified starch or a modified starch. For instance, the starch may bea pearl starch, a pregelatinized starch, an acid-modified starch, anextruded starch, etc. The starch may be modified such that it isethoxylated, ethylated, or acetylated. In addition, the starch may be acorn starch, a wheat starch, a milo starch, or other commerciallyavailable starch. Furthermore, the starch may include a combination ofstarches (e.g., migrating and non-migrating) in order to control thedispersibility of the sound damping polymer.

In addition, the hollow microspheres may include ceramic, glass,polymeric, etc. In one example, the hollow microsphere may be acenosphere. For instance, the microsphere may have a certain shell suchas one made of alumina, silica, or iron. In addition, the microspheresmay include a plurality of microspheres such as a combination of thosehaving a shell made of alumina, silica, or iron. In addition, themicrospheres may be filled with a gas (e.g., carbon dioxide, nitrogenand/or other inert gas, air, or a mixture thereof.).

The amount of carrier material employed is not necessarily limited. Forinstance, the carrier may be present in an amount of about 0.001 wt. %or more, such as 0.01 wt. % or more, such as 0.1 wt. % or more, such as0.5 wt. % or more, such as 1 wt. % or more, such as 2 wt. % or more,such as 3 wt. % or more, such as 5 wt. % or more, such as 10 wt. % ormore, such as 15 wt. % or more, such as 20 wt. % or more, such as 25 wt.% or more, such as 30 wt. % or more, such as 50 wt. % or more such as 75wt. % or more, such as 100 wt. % or more based on the weight of thesound damping polymer. The carrier may be present in an amount of 500wt. % or less, such as 400 wt. % or less, such as 300 wt. % or less,such as 200 wt. % or less, such as 100 wt. % or less, such as 90 wt. %or less, such as 80 wt. % or less, such as 70 wt. % or less, such as 50wt. % or less, such as 40 wt. % or less, such as 35 wt. % or less, suchas 25 wt. % or less based on the weight of the sound damping polymer.

In one embodiment, the gypsum core may include a first gypsum layer anda second gypsum layer. The first gypsum layer may be between the firstencasing layer (i.e., front of the board), in particular the sounddamping layer on the first encasing layer, and the second gypsum layer.In addition, the first gypsum layer may have a density greater than thesecond gypsum layer. Accordingly, the first gypsum layer may be formedwithout the use of a foaming agent or with a reduced amount of foamingagent, which may be utilized in forming the second gypsum layer. In thisregard, in one embodiment, the first gypsum layer may have the samecomposition as the second gypsum layer except that the second gypsumlayer may be formed using a foaming agent.

In one embodiment, the gypsum core may also include a third gypsumlayer. The third gypsum layer may be provided between the second gypsumlayer and a second encasing layer. Like the first gypsum layer, thethird gypsum layer may also be a dense gypsum layer. In particular, thethird gypsum layer may have a density greater than the second gypsumlayer. Accordingly, the third gypsum layer may be formed without the useof a foaming agent or with a reduced amount of foaming agent, which maybe utilized in forming the second gypsum layer. In this regard, in oneembodiment, the third gypsum layer may have the same composition as thesecond gypsum layer except that the second gypsum layer may be formedusing a foaming agent.

Furthermore, when utilized within the gypsum core, the sound dampingpolymer may be provided in any of the first gypsum layer, the secondgypsum layer, and/or the third gypsum layer. Alternatively, in oneembodiment, the sound damping polymer may be provided in only one ofsuch layers. In another embodiment, the sound damping polymer may beprovided in two of such layers. In a further embodiment, the sounddamping polymer may be provided in all three of the gypsum layers.

In this regard, when the gypsum core includes multiple gypsum layers,the gypsum slurry may be deposited in multiple steps for forming thegypsum core. For instance, each gypsum layer may require a separatedeposition of gypsum slurry. In this regard, with a first gypsum layerand a second gypsum layer, a first gypsum slurry may be depositedfollowed by a second gypsum slurry. The first gypsum slurry and thesecond gypsum slurry may have the same composition except that thesecond gypsum slurry may include a foaming agent or more foaming agentthan the first gypsum slurry. In this regard, in one embodiment, thefirst gypsum slurry may not include a foaming agent. Accordingly, thefirst gypsum slurry may result in a dense gypsum layer, in particular anon-foamed gypsum layer. Such gypsum layer may have a density greaterthan the gypsum layer formed from the second gypsum slurry, or foamedgypsum layer.

Similarly, when the gypsum core includes three gypsum layers, the gypsumslurry may be deposited in three steps for forming the gypsum core. Forexample, a first and second gypsum slurry may be deposited as indicatedabove and a third gypsum slurry may be deposited onto the second gypsumslurry. The third gypsum slurry and the second gypsum slurry may havethe same composition except that the second gypsum slurry may include afoaming agent or more foaming agent than the third gypsum slurry. Inthis regard, in one embodiment, the third gypsum slurry may not includea foaming agent. Accordingly, the third gypsum slurry may result in adense gypsum layer, in particular a non-foamed gypsum layer. Such gypsumlayer may have a density greater than the gypsum layer formed from thesecond gypsum slurry, or foamed gypsum layer.

The first gypsum layer may have a thickness that is 0.5% or more, suchas 1% or more, such as 2% or more, such as 3% or more, such as 4% ormore, such as 5% or more, such as 10% or more, such as 15% or more thethickness of the second (or foamed) gypsum layer. The thickness may be80% or less, such as 60% or less, such as 50% or less, such as 40% orless, such as 30% or less, such as 25% or less, such as 20% or less,such as 15% or less, such as 10% or less, such as 8% or less, such as 5%or less the thickness of the second (or foamed) gypsum layer. In oneembodiment, such relationship may also be between the third gypsum layerand the second gypsum layer.

The density of the second (or foamed) gypsum layer may be 0.5% or more,such as 1% or more, such as 2% or more, such as 3% or more, such as 4%or more, such as 5% or more, such as 10% or more, such as 15% or morethe density of the first (or non-foamed) gypsum layer. The density ofthe second (or foamed) gypsum layer may be 80% or less, such as 60% orless, such as 50% or less, such as 40% or less, such as 30% or less,such as 25% or less, such as 20% or less, such as 15% or less, such as10% or less, such as 8% or less, such as 5% or less the density of thefirst (or non-foamed) gypsum layer. In one embodiment, such relationshipmay also be between the third gypsum layer and the second gypsum layer.In addition, in one embodiment, all of the gypsum layers may have adifferent density.

In one embodiment, during the method of making the gypsum board, a sounddamping polymer may be provided on the gypsum core. The sound dampingpolymer may be as described herein. In this regard, the sound dampingpolymer may be present between the gypsum core and a second encasinglayer. When the gypsum core includes a first gypsum layer and a secondgypsum layer, the sound damping polymer and layer may be between thesecond gypsum layer and the second encasing layer. When the gypsum coreincludes a first gypsum layer, a second gypsum layer, and a third gypsumlayer, the sound damping polymer and layer may be between the thirdgypsum layer and the second encasing layer.

In addition, a second encasing layer may be provided on the sounddamping polymer or layer. However, like with the first encasing layerand the sound damping polymer, it should be understood that the sounddamping polymer may be provided offline or online. For instance, thesound damping polymer may be provided on the second encasing layersurface offline such that it is already provided on the second encasinglayer prior to use in the manufacture of the gypsum board. In thisregard, when providing the second encasing layer on the gypsum slurry,the sound damping polymer and layer will also automatically be providedbetween the gypsum layer and the second encasing layer. Alternatively,or in addition, the sound damping polymer may be provided inline duringthe manufacture of the gypsum board.

The encasing layer may be any encasing layer as generally employed inthe art. For instance, the encasing layer may be a paper encasing layer,a fibrous (e.g., glass fiber) mat encasing layer, or a polymericencasing layer. In general, the first encasing layer and the secondencasing layer may be the same type of material. Alternatively, thefirst encasing layer may be one type of material while the secondencasing layer may be a different type of material.

In one embodiment, the encasing layer may include a paper encasinglayer. For instance, both the first and second encasing layers may be apaper encasing layer. Alternatively, in another embodiment, the encasinglayer may be a glass mat encasing layer. For instance, both the firstand second encasing layers may be a glass mat encasing layer. In afurther embodiment, the encasing layer may be a polymeric encasinglayer. For instance, both the first and second encasing layers may be apolymeric encasing layer. In another further embodiment, the encasinglayer may be a metal encasing layer (e.g., an aluminum encasing layer).For instance, both the first and second encasing layers may be a metalencasing layer (e.g., an aluminum encasing layer).

After deposition of the stucco (calcined gypsum) slurry, the calciumsulfate hemihydrate reacts with the water to convert the calcium sulfatehemihydrate into a matrix of calcium sulfate dihydrate. Such reactionmay allow for the stucco to set and become firm thereby allowing for theboards to be cut at the desired length. In this regard, the method maycomprise a step of reacting calcium sulfate hemihydrate with water toform calcium sulfate dihydrate or allowing the calcium sulfatehemihydrate to convert to calcium sulfate dihydrate. In this regard, themethod may allow for the slurry to set to form a gypsum board.

The method may also comprise a step of cutting a continuous gypsum sheetinto a gypsum board. Then, after the cutting step, the method maycomprise a step of supplying the gypsum board to a heating or dryingdevice. For instance, such a heating or drying device may be a kiln andmay allow for removal of any free water. The temperature and timerequired for heating in such heating or drying device are notnecessarily limited by the present invention.

The present invention also discloses a gypsum board. The gypsum boardincludes a gypsum core having a first gypsum layer surface and a secondgypsum layer surface opposing the first gypsum layer surface. A firstsound damping layer may be disposed at a gypsum layer surface. Inparticular, a first sound damping layer may be disposed at a firstgypsum layer surface. In one embodiment, the first sound damping layermay be disposed directly onto the first gypsum layer surface. In anotherembodiment, the first sound damping layer may be disposed on an encasinglayer disposed on the first gypsum layer surface. In a furtherembodiment, a second sound damping layer may be disposed on anothergypsum layer surface. Such second sound damping layer may be disposed onan encasing layer disposed on the second gypsum layer surface. In thisregard, the gypsum board may include a first encasing layer, a firstsound damping layer, a gypsum core, a second sound damping layer, and asecond encasing layer.

In addition, when disposed, the sound damping layer may partially orentirely cover the respective surface or layer on which it is disposedor positioned. In one embodiment, the sound damping layer covers theentire surface or layer. In another embodiment, the sound damping layeronly partially covers the entire surface or layer. Further, the encasinglayer may entirely cover the respective surface or layer on which it isdisposed or positioned.

In addition, the sound damping layer may be a monolithic, homogeneouslayer. Alternatively, the sound damping layer may be a heterogeneous ordiscontinuous layer. Also, the sound damping layer may be provided inthe form of an adhesive or glue such that drying may be required inorder to form the sound damping layer. For instance, the sound dampinglayer may be formed from a precursor solution including any polymers asmentioned herein wherein the precursor solution is dried to form thesound damping layer.

In one embodiment, the aforementioned gypsum board may be sandwiched.For instance, two of the aforementioned gypsum boards may be sandwichedor glued together to form a composite gypsum board. Such compositegypsum board may provide further improvements in properties.

The sound damping gypsum board disclosed herein may have manyapplications. For instance, the gypsum board may be used as a standaloneboard in construction for the preparation of walls, ceilings, floors,etc. In addition, the sound damping gypsum board may be installed on anexisting or installed gypsum board, wall, or panel. As used in thepresent disclosure, the term “gypsum board,” generally refers to anypanel, sheet, or planar structure, either uniform or formed by connectedportions or pieces, that is constructed to at least partially establishone or more physical boundaries. Such existing, installed, or otherwiseestablished or installed wall or ceiling structures comprise materialsthat may include, as non-limiting examples, gypsum, stone, ceramic,cement, wood, composite, or metal materials. The installed gypsum boardforms part of a building structure, such as a wall or ceiling. Theinstallation of the sound damping gypsum board as disclosed herein canprovide a desired acoustical performance to an existing or installedgypsum board that does not have any sound damping capabilities orineffective sound damping abilities or can be used to further enhanceacoustical performance.

Regardless of the application, the gypsum board as disclosed hereinprovides the desired sound damping properties. In particular, the gypsumboard exhibits a decay time of 2 seconds or less, such as 1.8 seconds orless, such as 1.5 seconds or less, such as 1.3 seconds or less, such as1 second or less, such as 0.9 seconds or less, such as 0.8 seconds orless, such as 0.7 seconds or less, such as 0.6 seconds or less, such as0.5 seconds or less, such as 0.4 seconds or less, such as 0.3 seconds orless, such as 0.2 seconds or less, such as 0.1 seconds or less, such as0.01 seconds or less, such as 0.001 seconds or less. The decay time maybe 0.0001 seconds or more, such as 0.001 seconds or more, such as 0.01seconds or more, such as 0.01 seconds or more, such as 0.1 seconds ormore, such as 0.2 seconds or more, such as 0.3 seconds or more, such as0.4 seconds or more, such as 0.5 seconds or more, such as 0.6 seconds ormore, such as 0.7 seconds or more. In general, the lower the decay time,the better the performance of the gypsum board and sound dampingproperties. In one embodiment, the decay time may be reduced by at least10%, such as at least 20%, such as at least 30%, such as at least 40%,such as at least 50%, such as at least 60%, such as at least 70%, suchas at least 80%, such as at least 90%, such as at least 95% incomparison to a control board. For example, such control board may bethe same board as the inventive gypsum board except without the use ofthe sound damping polymer.

The thickness of the gypsum board, and in particular, the gypsum core,is not necessarily limited and may be from about 0.25 inches to about 1inch. For instance, the thickness may be at least ¼ inches, such as atleast 5/16 inches, such as at least ⅜ inches, such as at least ½ inches,such as at least ⅝ inches, such as at least ¾ inches, such as at least 1inch. In this regard, the thickness may be about any one of theaforementioned values. For instance, the thickness may be about ¼inches. Alternatively, the thickness may be about ⅜ inches. In anotherembodiment, the thickness may be about ½ inches. In a furtherembodiment, the thickness may be about ⅝ inches. In another furtherembodiment, thickness may be about 1 inch. In addition, at least twogypsum boards may be combined to create another gypsum board. Forexample, at least two gypsum boards having a thickness of about 5/16inches each may be combined or sandwiched to create a gypsum boardhaving a thickness of about ⅝ inches. While this is one example, itshould be understood that any combination of gypsum boards may beutilized to prepare a sandwiched gypsum board. With regard to thethickness, the term “about” may be defined as within 10%, such as within5%, such as within 4%, such as within 3%, such as within 2%, such aswithin 1%.

It should be understood that when a composite gypsum board containingtwo of the aforementioned gypsum boards is present, such composite maybe about twice the aforementioned thickness.

In addition, the board weight of the gypsum board is not necessarilylimited. For instance, the gypsum board may have a board weight of 500lbs/MSF or more, such as about 600 lbs/MSF or more, such as about 700lbs/MSF or more, such as about 800 lbs/MSF or more, such as about 900lbs/MSF or more, such as about 1000 lbs/MSF or more, such as about 1100lbs/MSF or more, such as about 1200 lbs/MSF or more, such as about 1300lbs/MSF or more, such as about 1400 lbs/MSF or more, such as about 1500lbs/MSF or more. The board weight may be about 7000 lbs/MSF or less,such as about 6000 lbs/MSF or less, such as about 5000 lbs/MSF or less,such as about 4000 lbs/MSF or less, such as about 3000 lbs/MSF or less,such as about 2500 lbs/MSF or less, such as about 2000 lbs/MSF or less,such as about 1800 lbs/MSF or less, such as about 1600 lbs/MSF or less,such as about 1500 lbs/MSF or less, such as about 1400 lbs/MSF or less,such as about 1300 lbs/MSF or less, such as about 1200 lbs/MSF or less.Such board weight may be a dry board weight such as after the boardleaves the heating or drying device (e.g., kiln).

In addition, the gypsum board may have a density of about 5 pcf or more,such as about 10 pcf or more, such as about 15 pcf or more, such asabout 20 pcf or more. The board may have a density of about 60 pcf orless, such as about 50 pcf or less, such as about 40 pcf or less, suchas about 35 pcf or less, such as about 33 pcf or less, such as about 30pcf or less, such as about 28 pcf or less, such as about 25 pcf or less,such as about 23 pcf or less, such as about 20 pcf or less.

The gypsum board may have a certain nail pull resistance, whichgenerally is a measure of the force required to pull a gypsum panel offof a wall by forcing a fastening nail through the panel. The valuesobtained from the nail pull test generally indicate the maximum stressachieved while the fastener head penetrates through the board surfaceand core. In this regard, the gypsum board exhibits a nail pullresistance of at least about 25 lb_(f), such as at least about 30pounds, such as at least about 35 lb_(f), such as at least about 40lb_(f), such as at least about 45 lb_(f), such as at least about 50lb_(f), such as at least about 55 lb_(f), such as at least about 60lb_(f), such as at least about 65 lb_(f), such as at least about 70lb_(f), such as at least about 75 lb_(f), such as at least about 77lb_(f), such as at least about 80 lb_(f), such as at least about 85lb_(f), such as at least about 90 lb_(f), such as at least about 95lb_(f), such as at least about 100 lb_(f) as tested according to ASTMC1396. The nail pull resistance may be about 150 lb_(f) or less, such asabout 140 lb_(f) or less, such as about 130 lb_(f) or less, such asabout 120 lb_(f) or less, such as about 110 lb_(f) or less, such asabout 105 lb_(f) or less, such as about 100 lb_(f) or less, such asabout 95 lb_(f) or less, such as about 90 lb_(f) or less, such as about85 lb_(f) or less, such as about 80 lb_(f) or less as tested accordingto ASTM C1396. Such nail pull resistance may be based upon the thicknessof the gypsum board. For instance, when conducting a test, such nailpull resistance values may vary depending on the thickness of the gypsumboard. As an example, the nail pull resistance values above may be for a⅝ inch board. However, it should be understood that instead of a ⅝ inchboard, such nail pull resistance values may be for any other thicknessgypsum board as mentioned herein.

The gypsum board may have a certain compressive strength. For instance,the compressive strength may be about 150 psi or more, such as about 200psi or more, such as about 250 psi or more, such as about 300 psi ormore, such as about 350 psi or more, such as about 375 psi or more, suchas about 400 psi or more, such as about 500 psi or more as testedaccording to ASTM C473. The compressive strength may be about 3000 psior less, such as about 2500 psi or less, such as about 2000 psi or less,such as about 1700 psi or less, such as about 1500 psi or less, such asabout 1300 psi or less, such as about 1100 psi or less, such as about1000 psi or less, such as about 900 psi or less, such as about 800 psior less, such as about 700 psi or less, such as about 600 psi or less,such as about 500 psi or less. Such compressive strength may be basedupon the density and thickness of the gypsum board. For instance, whenconducting a test, such compressive strength values may vary dependingon the thickness of the gypsum board. As an example, the compressivestrength values above may be for a ⅝ inch board. However, it should beunderstood that instead of a ⅝ inch board, such compressive strengthvalues may be for any other thickness gypsum board as mentioned herein.

In addition, the gypsum board may have a core hardness of at least about8 lb_(f), such as at least about 10 lb_(f), such as at least about 11lb_(f), such as at least about 12 lb_(f), such as at least about 15lb_(f), such as at least about 18 lb_(f), such as at least about 20lb_(f) as tested according to ASTM C1396. The gypsum board may have acore hardness of 50 lb_(f) or less, such as about 40 lb_(f) or less,such as about 35 lb_(f) or less, such as about 30 lb_(f) or less, suchas about 25 lb_(f) or less, such as about 20 lb_(f) or less, such asabout 18 lb_(f) or less, such as about 15 lb_(f) or less as testedaccording to ASTM C1396. In addition, the gypsum board may have an endhardness according to the aforementioned values. Further, the gypsumboard may have an edge hardness according to the aforementioned values.Such core hardness may be based upon the thickness of the gypsum board.For instance, when conducting a test, such core hardness values may varydepending on the thickness of the gypsum board. As an example, the corehardness values above may be for a ⅝ inch board. However, it should beunderstood that instead of a ⅝ inch board, such core hardness values maybe for any other thickness gypsum board as mentioned herein.

EXAMPLES Example 1

This example demonstrates use of the sound damping polymer between anencasing layer and the gypsum core by providing the polymer at theinterface of an encasing layer and the gypsum slurry. When utilized, 30grams of the sound damping polymer were provided to form the sounddamping layer.

Samples were tested for decay time using SigView software made bySignalLab. Nominal 12″ by 12″ samples were suspended on a wire andimpacted on one side with consistent force using a hammer with anaccelerometer affixed to the opposite side from the point of impact. Thedecay time was determined through the software interface by denoting theperiod between the initial time of impact with the sample and the timewhen the amplitude of the sound signal approached zero. The average ofthree tests was used to report sample decay time.

Thickness Weight Decay Time Sample (inches) (lbs/MSF) (seconds) ½″Series Control board without any 0.50 2470 1.51 sound damping polymerSound damping polymer 0.50 2470 0.67 applied to interior of encasinglayer (no additives mixed with polymer) Sound damping polymer 0.50 24900.72 applied to interior of encasing layer—(land plaster blended withpolymer) Sound damping polymer 0.50 2490 0.78 applied to interior ofencasing layer—(cellulose fibers blended with polymer) Sound dampingpolymer on 0.50 2580 0.89 exterior of encasing layer with additionalencasing layer over polymer ⅝″ Inch Series Control board including two0.625 2590 0.31 ¼″ panels sandwiched and glued with sound dampingpolymer Control board without any 0.625 2890 0.87 sound damping polymerSound damping polymer 0.625 2980 0.62 on exterior of encasing layer withadditional encasing layer over polymer Board with sound damping 0.6252730 0.47 polymer applied to interior of encasing layer Sandwich SeriesControl board using two 1.00 4940 0.34 ½″ boards with no sound dampingpolymer Board with no sound damping 1.00 5050 0.38 polymer in the core +Board with sound damping polymer between encasing layer and a secondexterior encasing layer Board with no sound damping 1.00 4940 0.24polymer in the core + Board with sound damping polymer applied tointerior of encasing layer Control board using two 1.00 4970 0.23 ½″boards with sound damping polymer between the boards

Example 2

This example demonstrates use of the sound damping polymer between anencasing layer and the gypsum core by providing the polymer at theinterface of an encasing layer and the gypsum slurry. The thickness ofthe boards was ⅝ inches. When utilized, 30 grams of the sound dampingpolymer were provided to form the sound damping layer.

Samples were tested for decay time using SigView software made bySignalLab. Nominal 12″ by 12″ samples were suspended on a wire andimpacted on one side with consistent force using a hammer with anaccelerometer affixed to the opposite side from the point of impact. Thedecay time was determined through the software interface by denoting theperiod between the initial time of impact with the sample and the timewhen the amplitude of the sound signal approached zero. The average ofthree tests was used to report sample decay time.

Weight Decay Time Sample (lbs/MSF) (seconds) Control conventional sounddamping 2707 0.213 gypsum board comprising a monolithic damping layerglued between two 5/16″ panels Control gypsum board 3040 0.730 Sounddamping polymer applied to 3024 0.310 interior of paper encasing layerSound damping polymer applied to 3012 0.421 interior of paper encasinglayer in grid pattern Sound damping polymer applied to 3110 0.506interior of glass mat encasing layer Sound damping polymer applied to3040 1.445 interior of glass mat encasing layer

While particular embodiments of the present disclosure have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the present disclosure. It istherefore intended to cover in the appended claims all such changes andmodifications that are within the scope of this disclosure.

1. A method of forming a gypsum board, the method comprising: providinga first encasing layer and a first sound damping layer on the firstencasing layer wherein the sound damping layer includes at least 50 wt.% of a first sound damping polymer, depositing a gypsum slurrycomprising stucco and water on the sound damping layer to form a gypsumcore, providing a second encasing layer on the gypsum slurry, andallowing the stucco to convert to calcium sulfate dihydrate.
 2. Themethod of claim 1, further comprising providing a second sound dampinglayer between the gypsum slurry and the second encasing layer.
 3. Themethod of claim 1, wherein the gypsum core includes a first gypsum layerand a second gypsum layer, the first gypsum layer having a densitygreater than the second gypsum layer.
 4. The method of claim 1, whereinthe first sound damping polymer comprises a viscoelastic polymer.
 5. Themethod of claim 1, wherein the first sound damping layer includesrubber, cork, or a mixture thereof.
 6. The method of claim 1, whereinthe first sound damping layer includes a cellulosic material, glycerin,or a mixture thereof.
 7. The method of claim 1, wherein the sounddamping layer includes an additive also included in the gypsum slurry.8. The method of claim 1, wherein the first sound damping polymercomprises an acrylic polymer or copolymer.
 9. The method of claim 1,wherein the sound damping layer includes at least 90 wt. % of the firstsound damping polymer.
 10. The method of claim 1, wherein the gypsumcore further comprises a starch.
 11. The method of claim 1, wherein thefirst sound damping polymer is present in an amount of from 0.001lbs/MSF to 150 lbs/MSF based on the weight of the gypsum board.
 12. Themethod of claim 1, wherein the gypsum slurry further includes a secondsound damping polymer.
 13. The method of claim 1, wherein the sounddamping layer is directly between the first encasing layer and thegypsum slurry.
 14. The method of claim 1, wherein the sound dampinglayer comprises gypsum.
 15. The method of claim 1, wherein the sounddamping layer comprises a pigment.
 16. The method of claim 1, whereinthe sound damping layer comprises calcium carbonate.
 17. The method ofclaim 1, wherein the sound damping layer comprises magnesium carbonate.18. The method of claim 1, wherein the sound damping layer comprises aninorganic particle.
 19. The method of claim 1, wherein the gypsum boardexhibits a sound transmission loss of 20% or more in comparison to aboard without the sound damping layer.
 20. The method of claim 1,wherein the first sound damping polymer is provided in a formulationhaving a viscosity of from 500 cps to 15000 cps.
 21. A gypsum boardformed from the method of claim 1.